Difference between revisions of "HEPES"

From OpenWetWare
Jump to: navigation, search
(added tag)
m
Line 1: Line 1:
 
N-(2-hydroxyethyl)piperazine-N’-(2-ethanesulfonic acid); 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; CAS NUMBER: 7365-45-9
 
N-(2-hydroxyethyl)piperazine-N’-(2-ethanesulfonic acid); 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; CAS NUMBER: 7365-45-9
  
A Good buffer <cite>Good66</cite><cite>Good74</cite><cite>Blanchard84</cite>.  Stable pH vs. temperature, no primary amine groups, no metal chelation, near physiologic pH range.
+
A Good buffer <cite>Good66</cite><cite>Good74</cite><cite>Blanchard84</cite>.  Stable pH vs. temperature, no primary amine groups, no metal chelation, near physiologic pH range. HEPES is often used to maintain protein solubility in biochemical experiments.
  
 
* pK<sub>a</sub> at 25C of 7.55 (7.31 at 37C)
 
* pK<sub>a</sub> at 25C of 7.55 (7.31 at 37C)
Line 8: Line 8:
 
* molecular weight 238.3
 
* molecular weight 238.3
 
* &Delta;pK<sub>a</sub>/&Delta;T = -.014
 
* &Delta;pK<sub>a</sub>/&Delta;T = -.014
*HEPES contains tertiary amines, which are reactive under certain conditions. See its structure in the [http://www.sigmaaldrich.com/catalog/search/ProductDetail/SIGMA/H3375 Sigma catalog].
+
* HEPES contains tertiary amines, which are reactive under certain conditions.  
*Chemical formula: C<sub>8</sub>H<sub>18</sub>N<sub>2</sub>O<sub>4</sub>S
+
* See the structure of [http://store.p212121.com/products/HEPES-500-g.html HEPES].
 +
* Chemical formula: C<sub>8</sub>H<sub>18</sub>N<sub>2</sub>O<sub>4</sub>S
  
 
Buffers are typically 1 M, prepared by neutralizing HEPES with sodium hydroxide.  HEPES is essentially insoluble until it is neutralized.
 
Buffers are typically 1 M, prepared by neutralizing HEPES with sodium hydroxide.  HEPES is essentially insoluble until it is neutralized.

Revision as of 20:19, 30 July 2010

N-(2-hydroxyethyl)piperazine-N’-(2-ethanesulfonic acid); 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; CAS NUMBER: 7365-45-9

A Good buffer [1][2][3]. Stable pH vs. temperature, no primary amine groups, no metal chelation, near physiologic pH range. HEPES is often used to maintain protein solubility in biochemical experiments.

  • pKa at 25C of 7.55 (7.31 at 37C)
  • a second pKa at pH 3 is not of interest
  • usable buffering range of 6.8 to 8.2
  • molecular weight 238.3
  • ΔpKa/ΔT = -.014
  • HEPES contains tertiary amines, which are reactive under certain conditions.
  • See the structure of HEPES.
  • Chemical formula: C8H18N2O4S

Buffers are typically 1 M, prepared by neutralizing HEPES with sodium hydroxide. HEPES is essentially insoluble until it is neutralized.

  1. Good NE, Winget GD, Winter W, Connolly TN, Izawa S, and Singh RM. Hydrogen ion buffers for biological research. Biochemistry. 1966 Feb;5(2):467-77. PubMed ID:5942950 | HubMed [Good66]
  2. Good NE and Izawa S. Hydrogen ion buffers. Methods Enzymol. 1972;24:53-68. PubMed ID:4206745 | HubMed [Good74]
  3. Blanchard JS. Buffers for enzymes. Methods Enzymol. 1984;104:404-14. PubMed ID:6717292 | HubMed [Blanchard84]
All Medline abstracts: PubMed | HubMed and